Lecture on the Dermis

Introduction

• This lecture focuses on the dermis, differentiating it from the epidermis.
• The dermis is thicker than the epidermis and forms the bulk of the skin (0.2 to 4 mm thick).
• Leather is made from the dermis.

Structure of the Dermis

• Two Layers of the Dermis:
  1. Papillary Layer
     • Superficial and thin layer.
     • Composed of areolar connective tissue.
     • Contains collagen fibers (strength) and elastin fibers (stretchability).
     • Rich in blood vessels.
     • Features dermal ridges (invaginations into the epidermis) which enhance grip (notably on palms and soles).
     • Papillary means nipple-like projections.
  2. Reticular Layer
     • Makes up 80% of the dermis' thickness.
     • Composed of dense irregular connective tissue.
     • Contains mainly collagen fibers arranged haphazardly.
     • Very strong and flexible, resistant to tearing.
     • Less vascular compared to the papillary layer.

Features and Functions

• Accessory Structures:
  • Hair roots.
  • Various glands.
  • Specialized muscles.
  • Nerves.
• Vasculature:
  • Blood vessels in the papillary layer and at the base of the reticular layer.
  • Papillary layer contains many blood vessels; known for being vascular.
  • Dense irregular connective tissue in the reticular layer is not very vascular.
  • Important for understanding body temperature regulation.

Conclusion

• The dermis contains more interesting features compared to the epidermis due to the presence of accessory structures and vascularity.
• Further discussion on glands and other structures will follow in subsequent lectures.